168 



THE SOUTHE 



RN PLANTER. 



produce seed, and a whole field may frequently 

 be examined without finding a single ball. — 

 The crop has wonderfully decreased in quan- 

 tity. Five hundred bushels were once consi- 

 dered only a fair crop, with only ordinary care 

 in cultivating and manuring. 



That this loss of vitality proceeds from the 

 long propagation of potatoes from cutting in- 

 stead of by seed, is a fair inference from the 

 known laws of nature. Every plant bears 

 within it the principle of decay and disor- 

 ganization from old age. Now, the plant 

 raised from a cutting is but the prolongation 

 of another plant, and must feel the effect of 

 this law of nature in some measure at least. 

 From this cause we find that though almost 

 every plant may be propagated from a cutting 

 as well as from seed. The latter method only 

 can be perpetual. The best fruits of former 

 times have all past away, and the varieties 

 which we now have are the products of seed- 

 lings. 



That the diminution of the vitality of the 

 potato is owing to their having been thus pro- 

 pagated for too long a time, may, therefore, be 

 regarded as exceedingly probable. But that 

 this is the cause of the present disease is not 

 so certain. By Dr. Smee, whose attention has 

 been long devoted to it, this theory is said to 

 be expressly contradicted by facts. He de- 

 clares that he has constantly observed the 

 disease upon potatoes which he reared from 

 the seed, as well as upon those which had 

 been propagated in the common method. We 

 have not had an opportunity of bringing it to 

 this test ourselves, but if this fact may be re- 

 garded as established, it overthrows this theo- 

 ry of the disease. 



The last alleged cause which we shall no- 

 tice is, that it is the result of a small insect, 

 known among naturalists as the alpkis vastator, 

 which has been observed to have been extra- 

 ordinarily prevalent among potato vines dur- 

 ing the few past years. It is very small in 

 size, and may be seen settled on the underside 

 of the leaves of the plant. It lives upon the 

 juices of the plant, which it sucks away by 

 means of the apparatus which it inserts in the 

 leaf. It takes away a portion of the sap ne- 

 cessary to form the substance of the stem and 



root. Thus the proper qualities of the sap 

 are destroyed, and it no longer returns the ma- 

 terials for the starch and cellular tissue of the 

 plant. The natural vital functions being thus 

 interfered with, the growth is impaired, and 

 putrefaction and other changes begin in va- 

 rious parts. 



Dr. Smee remarks, " The essence of the 

 disease is a disturbance of the relation exist- 

 ing between the plant and the root, and conse- 

 quently the sap and the cellular substance do 

 not bear such proper relation as fits them for 

 the performance §f the vital functions; and 

 this being the case, the vital functions neces- 

 sarily cease, and the plant dies." 



The turnip and the beet suffer from the at- 

 tacks of this insect as the potato does. It 

 also attacks wild plants, but the injury to them, 

 is very slight. It is only plants whose roots 

 and underground stem have been unduly cul- 

 tivated and increased, that are devastated by 

 it in the manner which we have seen. For 

 the reason that the relation between plant and 

 root in these plants will not bear to be further 

 interfered with. 



In the potatoes grown from the cutting the 

 disease will be propagated from the plant, be- 

 cause each new plant is merely an extension 

 of the old one. This propagation of the dis- 

 ease gives rise to all those phenomena observed 

 in the present potato rot. 



If this theory of the disease be correct, the 

 future prospects of the potato crop are ex- 

 tremely uncertain. They depend upon the 

 continuance of the present number of the in- 

 sect. If they continue to increase, the pros- 

 pect is appalling. This crop must be annihi- 

 lated. But nature does not long allow any 

 animal 10 maintain an undue proportion to 

 the rest of the animal kingdom. There are 

 abundance of instances on record of particular 

 insects making their appearance in great num- 

 bers, and after a while disappearing. There 

 are many ways by which the balance may be 

 restored. And after they disappear, the dis- 

 ease will probably wear itself out in a little 

 while, or we may obtain healthy plants from 

 the seed. Such a consummation is devoutly 

 to be wished for. 



